Server blades, also known as blade servers, are data processing systems that are built on cards and that plug into slots in a rack, also known as a chassis. For example, a chassis may feature numerous vertical slots, and multiple server blades for handling application workloads may be plugged into those slots like books on a bookshelf. Server blades may therefore be referred to as modular computing components or platforms. International Business Machines (IBM) Corporation, for example, sells a line of server blades under the BladeCenter trademark. Such a server blade may use two processors, such as the processors referred to by Intel Corporation as Xeon processors. Other types of server blades may use different types and numbers of processors.
The chassis may contain a backplane and/or an interconnect module with buses or communication lines interconnecting the slots in the rack. In addition, a chassis management module (CMM) may be plugged into the rack, for monitoring the resources within the chassis, for providing management warning or alerts, for receiving management directives, and for performing other administrative functions associated with the server blades. The chassis may also contain many other types of components or modules, such as shared power modules, storage blades containing hard disk drives, input/output (I/O) blades for optical or other types of I/O, etc. For purposes of this disclosure, the term server blade includes I/O blades and similar modules.
Server blades are typically small, and it is typically relatively easy to install additional server blades into a chassis. Server blades therefore typically provide better density and scalability than standalone servers. Consequently, a significant amount of software has been developed to provision, configure, manage, and support such modular, scalable components, including software for remotely managing the hardware, and software for apportioning different sets of blades for use by different software applications. For instance, the management software may group multiple server blades together to cooperate in handling the processing workload of a software application such as a web server, for example. Thus, multiple blades may operate more or less as a virtual unified processing system.
The software for apportioning blades for different applications may also provide for automatic reapportionment in response to changing conditions. For example, blades may be reapportioned in response to changes in the workload being handled by one or more applications, or in response to hardware or software errors in one or more blades. In some instances, blades and chassis may include hardware and/or software to support autonomous monitoring and recovery features, in accordance with a specification such as the Intelligent Platform Management Interface (IPMI) Specification, Second Generation, v2.0, Revision 1.0, dated Feb. 12, 2004.
A different approach to data processing is to partition a single platform or server into multiple virtual machines, with an independent operating system (OS) and independent software applications running in each virtual machine. For instance, a company named VMWare provides software that supports partitioning a single physical processing system into multiple virtual machines. The software provided under the name Connectix Virtual PC by Microsoft Corporations also supports partitioning a single platform into multiple virtual machines.